A combined radical and non-radical oxidation processes for efficient degradation of Acid Orange 7 in the homogeneous Cu(II)/PMS system: important role of chloride

Environmental Science and Pollution Research - Trace copper ion (Cu(II)) in water and wastewater can trigger peroxymonosulfate (PMS) activation to oxidize organic compounds, but it only works under...     

Effect of pressure and atmosphere during hydrothermal treatment on the properties of sewage sludge-derived solid fuel

Journal of Material Cycles and Waste Management - Efforts to improve the performance of hydrothermal treatment (HT) in producing high-quality solid fuel from sewage sludge were carried out by...     

中国可持续社会养老保险的综合评价体系和实证分析

我国可持续社会养老保险的综合评价指标体系包括四个层次和三级子系统，内容涉及养老保险人数、机构设置、基金管理和代际平衡四个子目标。应用因子分析模糊综合评价方法对我国1990-2001年养老保险建设状况进行评价，本文认为基金管理，行政管理和代际失衡是影响我国可持续养老保险发展的主要因素。     

铅锌矿区玉米中重金属污染特征及健康风险评价

以西南某铅锌矿区为研究区域,测定了92份玉米样品中Pb、Zn、Cd、Cr和Ni的含量,开展了矿区玉米籽粒中重金属污染特征及健康风险研究.应用单因子污染指数和内梅罗综合污染指数分析了重金属在玉米中的污染状况,采用健康风险评价模型评价了重金属对人体健康造成的风险,同时利用主成分分析法解析了重金属的主要来源.结果表明,玉米籽粒中Pb、Zn、Cd、Cr和Ni的平均含量分别为0.30、23.75、0.21、1.33和1.15 mg ·kg^-1;除重金属Zn外,其他4种重金属均超过我国食品卫生标准限值,研究区玉米籽粒中Pb、Cd、Cr和Ni的综合污染指数范围介于4.32~9.07之间,均属于重度污染,Zn的综合污染指数小于1;重金属通过玉米籽粒摄入引起的复合重金属污染对成人和儿童均存在健康风险,且对儿童造成的健康风险高于成人.玉米籽粒中5种重金属可以由2个主成分来反映,第一主成分主要支配Pb、Cd、Cr和Ni的来源,第二主成分支配Zn的来源.玉米籽粒重金属含量与土壤重金属含量之间没有明显相关性.     

船舶排放及不确定性对中国空气质量的影响

船舶排放是我国沿海地区重要的人为排放源,但现有的船舶排放评估研究大多只关注区域尺度的影响分析,而且忽视了排放清单的不确定性,这在一定程度上削弱了评估结果的可靠性.为此,本文利用WRF-SMOKE-CAMQ空气质量模型,定量评估了船舶排放及其不确定性对我国七大沿海港口城市夏季空气质量的影响,结果表明：船舶排放对我国主要沿海港口城市的SO₂、NO_x和PM_2.5浓度贡献范围分别为16.5%~62.5%、21.9%~72.9%和5.9%~26.0%,尤其对宁波、青岛和深圳等港口城市空气质量的影响显著,主要是由于港口较高的船舶排放以及气象传输两方面原因造成的;如果考虑船舶排放清单的总量不确定性,船舶排放对沿海港口城市夏季SO₂、NO_x和PM_2.5的影响分别呈现1.0~3.1,2.1~5.5,0.3~0.9μg/m³的波动;考虑船舶排放清单的时空分配不确定性,船舶排放对沿海港口城市夏季SO₂、NO_x和PM_2.5的影响分别呈现1.9~15.7,5.1~29.3,0.6~2.5μg/m³的波动.可见,船舶排放清单的不确定性对沿海城市船舶排放贡献影响量化有明显的影响.所以在评估船舶排放对港口城市空气质量的影响时,要考虑船舶排放清单的不确定性,尤其是时空分配的不确定性.而合理的时空分配能够提高船舶排放清单的质量和对沿海空气质量模拟的准确性.     

2018年春节期间京津冀地区污染过程分析

为了解2018年春节期间京津冀地区空气污染情况,利用近地面污染物浓度数据、激光雷达组网观测数据,结合WRF气象要素、颗粒物输送通量和HYSPLIT气团轨迹综合分析污染过程.结果表明,春节期间出现3次污染过程.春节前一次污染过程,各站点PM_2.5浓度均未超过200μg/m³;除夕夜,廊坊站点PM_2.5峰值浓度达到504μg/m³,是清洁天气的26倍;年初二~初五,各站点PM_2.5始终高于120μg/m³,且污染主要聚集在500m高度以下,北京地区存在高空传输,800m处最大输送通量达939μg/（m³·s）,此次重污染过程为一次典型的区域累积和传输过程.京津冀地区处于严格管控状态时,燃放烟花爆竹期间PM_2.5峰值浓度可达无燃放时PM_2.5峰值的3.2倍.为防止春节期间重污染现象的发生,需对静稳天气下燃放烟花炮竹采取预防对策.     

二乙烯三胺五甲叉膦酸酸解磷尾矿的实验探究

为减少磷尾矿堆积带来的环境污染问题,实现磷尾矿的钙、镁、磷元素的分离,以高镁磷尾矿为原料,采用二乙烯三胺五甲叉膦酸(DTPMP)进行酸解,探究磷尾矿中主要物相在DTPMP中的分解机制,并通过单因素实验探究pH、反应时间、反应温度及投料比对磷尾矿中MgO、CaO和P_2O_5分解率的影响。实验结果表明:pH对P_2O_5的分解率影响较大,高温更有利于尾矿中镁的溶出,在pH为2. 5,反应时间为60 min,反应温度为80℃,投料比为1. 56时,MgO、CaO和P_2O_5的分解率分别达到61. 05%、38. 23%和9. 67%。     

Bioassay: A useful tool for evaluating reclaimed water safety

Wastewater reclamation and reuse has been proved to be an effective way to relieve the fresh water crisis. However, toxic contaminants remaining in reclaimed water could lead to potential risk for reuse, and the conventional water quality standards have difficulty guaranteeing the safety of reclaimed water. Bioassays can vividly reflect the integrated biological effects of multiple toxic substances in water as a whole, and could be a powerful tool for evaluating the safety of reclaimed water. Therefore, in this study, the advantages and disadvantages of using bioassays for evaluating the safety of reclaimed water were compared with those of conventional water quality standards. Although bioassays have been widely used to describe the toxic effects of reclaimed water and treatment efficiency of reclamation techniques, a single bioassay cannot reflect the complex toxicity of reclaimed water, and a battery of bioassays involving multiple biological effects or in vitro tests with specific toxicity mechanisms would be recommended. Furthermore, in order to evaluate the safety of reclaimed water based on bioassay results, various methods including potential toxicology, the toxicity unit classification system, and a potential eco-toxic effects probe are summarized as well. Especially, some integrated ranking methods based on a bioassay battery involving multiple toxicity effects are recommended as useful tools for evaluating the safety of reclaimed water, which will benefit the promotion and guarantee the rapid development of the reclamation and reuse of wastewater.     

Influence of floc dynamic protection layer on alleviating ultrafiltration membrane fouling induced by humic substances

Cake layer formation is inevitable over time for ultrafiltration (UF) membrane-based drinking water treatment. Although the cake layer is always considered to cause membrane fouling, it can also act as a “dynamic protection layer”, as it further adsorbs pollutants and dramatically reduces their chance of getting to the membrane surface. Here, the UF membrane fouling performance was investigated with pre-deposited loose flocs in the presence of humic acid (HA). The results showed that the floc dynamic protection layer played an important role in removing HA. The higher the solution pH, the more negative the floc charge, resulting in lower HA removal efficiency due to the electrostatic repulsion and large pore size of the floc layer. With decreasing solution pH, a positively charged floc dynamic protection layer was formed, and more HA molecules were adsorbed. The potential reasons were ascribed to the smaller floc size, greater positive charge, and higher roughness of the floc layer. However, similar membrane fouling performance was also observed for the negative and positive floc dynamic protection layers due to their strong looseness characteristics. In addition, the molecular weight (MW) distribution of HA also played an important role in UF membrane fouling behavior. For the small MW HA molecules, the chance of forming a loose cake layer was high with a negatively charged floc dynamic protection layer, while for the large MW HA molecules it was high with a positively charged floc dynamic protection layer. As a result, slight UF membrane fouling was induced.     

Influence of environmental factors on arsenic accumulation and biotransformation using the aquatic plant species Hydrilla verticillata

Hydrilla verticillata(waterthyme) has been successfully used for phytoremediation in arsenic(As) contaminated water.To evaluate the effects of environmental factors on phytoremediation,this study conducted a series of orthogonal design experiments to determine optimal conditions,including phosphorus(P),nitrogen(N),and arsenate(As(Ⅴ))concentrations and initial pH levels,for As accumulation and biotransformation using this aquatic plant species,while also analyzing As species transformation in culture media after 96-hr exposure.Analysis of variance and the signal-to-noise ratio were used to identify both the effects of these environmental factors and their optimal conditions for this purpose.Results indicated that both N and P significantly impacted accumulation,and N was essential in As species transformation.High N and intermediate P levels were critical to As accumulation and biotransformation by H.verticillata,while high N and low P levels were beneficial to As species transformation in culture media.The highest total arsenic accumulation was(197.2±17.4) μg/g dry weight when As(V) was at level 3(375μg/L),N at level 2(4 mg/L),P at level 1(0.02 mg/L),and pH at level 2(7).Although H.verticillata is highly efficient in removing As(Ⅴ) from aquatic environments,its use could be potentially harmful to both humans and the natural environment due to its release of highly toxic arsenite.For cost-effective and ecofriendly phytoremediation of As-contaminated water,both N and P are helpful in regulating As accumulation and transformation in plants.